1. Field of Invention
The present invention relates generally to mobile communication devices. More particularly, at least one embodiment of the invention relates to high isolation switches for use in mobile communication devices.
2. Discussion of Related Art
Mobile communication devices, such as cellular phones, two-way radios, etc., having a transceiver for transmitting and receiving communication signals generally include a radio frequency (RF) switch to switch the antenna between a receive path and a transmit path. In addition, RF switches can be used to provide operation of the device in more than one frequency band. For example, multiple different communication standards, such as the Global System for Mobile (GSM) communication standard (utilized frequently in Europe and Asia) and the Code Division Multiple Access (CDMA) communication standard (utilized frequently in the United States) exist for cellular phone use, and these different standards require operation in different frequency bands. There is a growing demand for cellular phones and other mobile communication devices to be compatible with more than one communication standard. Therefore many devices include separate circuits to accommodate different communication standards, and use an RF switch to selectively alternate between the different circuits to operate the device in a desired mode.
These RF switches are generally located in close proximity to the antenna of the communication device. Accordingly, high isolation switches are desired as it is important to limit noise leakage and/or harmonic interference between the transmit and receive paths, or between different transmit or different receive paths in the device. In addition, it is desirable that the switch have low loss associated therewith to reduce power consumption and preserve battery life in a mobile device. Furthermore, because mobile communication devices are typically small, the components are located in very close proximity to one another, making electronic isolation, and therefore noise reduction, more important since there may be little isolation resulting from physical separation of the components. Furthermore, because many mobile communication devices are generally low power devices, even a relatively low level of noise may result in power loss that negatively impacts the performance of the device, and therefore good isolation between components is desirable.